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In computing, keyboard interrupt may refer to: A special case of signal (computing) , a condition (often implemented as an exception) usually generated by the keyboard in the text user interface A hardware interrupt generated when a key is pressed or released, see keyboard controller (computing)
In particular, the POSIX specification and the Linux man page signal (7) require that all system functions directly or indirectly called from a signal function are async-signal safe. [6] [7] The signal-safety(7) man page gives a list of such async-signal safe system functions (practically the system calls), otherwise it is an undefined behavior ...
IRQ 4 – serial port controller for serial port 1 (shared with serial port 3, if present) IRQ 5 – parallel port 3 or ISA sound card; IRQ 6 – floppy disk controller; IRQ 7 – parallel port 1 (shared with parallel port 2, if present). It can also be potentially be shared with a secondary ISA sound card with careful management of the port.
The interrupt priority level (IPL) is a part of the current system interrupt state, which indicates the interrupt requests that will currently be accepted. The IPL may be indicated in hardware by the registers in a programmable interrupt controller, or in software by a bitmask or integer value and source code of threads. [1]
For example, pressing a key on a computer keyboard, [1] or moving the mouse, triggers interrupts that call interrupt handlers which read the key, or the mouse's position, and copy the associated information into the computer's memory. [2] An interrupt handler is a low-level counterpart of event handlers.
Current interrupt systems are rather lackadaisical when compared to some highly tuned earlier ones, but the general increase in hardware performance has greatly mitigated this.) Hybrid approaches are also possible, wherein an interrupt can trigger the beginning of some burst of asynchronous I/O, and polling is used within the burst itself.
The IRR specifies which interrupts are pending acknowledgement, and is typically a symbolic register which can not be directly accessed. The ISR register specifies which interrupts have been acknowledged, but are still waiting for an end of interrupt (EOI). The IMR specifies which interrupts are to be ignored and not acknowledged.
For the "interrupt acknowledge" method, the external device gives the CPU an interrupt handler number. The interrupt acknowledge method is used by the Intel Pentium and many older microprocessors. [8] When the CPU is affected by an interrupt, it looks up the interrupt handler in the interrupt vector table, and transfers control to it.